ON Semiconductor FL7760LED1GEVK Evaluation Board User Manual

: June 8, 2024
: ON Semiconductor

Table of Contents

OVERVIEW
THEORY OF OPERATION
SCHEMATIC
TEST PROCEDURE
TEST DATA
THERMAL IMAGE
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FL7760LED1GEVK
3W SPI Controllable LED
Driver Evaluation Board
www.onsemi.com
EVAL BOARD USER’S MANUAL

FL7760LED1GEVK
Evaluation Board

OVERVIEW

This manual covers the specification, theory of operation, testing and construction of the FL7760LED1GEVK demonstration kit. The FL7760 kit demonstrates a 1 A buck LED driver intended for a single high−power LED. The SPI (Serial Peripheral Interface) bus does both analog and PWM dimming. The kit includes a load/SPI interface board to facilitate operation of the driver. The driver can be driven independently from any SPI controller. The nominal input voltage is 12 V.
Table 1. SPECIFICATIONS

Input Voltage| 10.8 V dc − 13.2 V dc|
---|---|---
Output Voltage| 2.5 V dc − 5.0 V dc|
Output Current| 1 A| Max
Output Ripple| 40 mA| P−P
Efficiency| 85%| Typ.
Switching Frequency| 200 kHz|
Rise/Fall Time| < 20µs|
Dimming Interface| SPI|
Dimming Resolution| 8 bits|
PCB Size| 30 mm × 30 mm|

The key features of this demo kit include:

Low Parts Count
Single Sided Assembly
Small Footprint
Very Fast Rise/Fall Times
SPI Dimming Control for Analog and PWM Dimming
12 V Operation
Integrated Thermal Shutdown and UVLO

THEORY OF OPERATION

Power Stage
The power stage is a CCM inverted buck converter. The output inductor sets the switching frequency because the control operates in hysteretic control mode. The peak and valley current are fixed percentages of the current reference. This fixes the inductor ripple current and eliminates the need for closed loop compensation. A novel high side current sense enables direct accurate control of the output current.
FL7760LED1GEVK
HV Start
The FL7760 supplies its own Vcc power greatly simplifying implementation. The input voltage range is 8 V − 70V. The internal Vcc regulates to 5 V ± 10%. The internal Vcc supplies a 3.3 V LDO for powering the DAC. The regulator and DAC draw less than 1mA combined.
Dimming
The FL7760 dim input controls both amplitude and on/off control. This makes the dim interface controllable by analog, PWM, or both at the same time. The DAC has an output range of 0 V – 3.3 V for 8 bits of resolution. A dim signal below 0.5 V turns off the output and a dim signal above 3 V is 100% output.
Protection
Thermal Protection
The thermal protection is built into the FL7760 and shuts down the FL7760 when the die temperature exceeds 150°C.
OVP
The output voltage is inherently limited to be less than or equal to Vin. As such, no OVP is required due this inherent limitation.
Load Board Operation
The load board connects to the LED driver via an 8 conductor FPC cable. The FPC cable makes a simple and convenient interconnection. The load board serves 2 major functions: 1) provide an easy connection to an LED load 2) provide a USB−SPI bridge for computer control of the LED driver.
The daughter card on the load has a mini USB−A connection for attachment to your computer. See the test procedure for details of the setup of the SPI terminal application.

SCHEMATIC

FL7760LED1GEVK

Table 2. BILL OF MATERIAL

Qty| Reference| Part| Distributor| Dist. P/N| Manufacturer| Mfr_PN
---|---|---|---|---|---|---
4| C1, C2, C3, C4| 4.7 uF 25 V| Digikey| 1276−3178−1−ND| Samsung| CL31B475KAHNNWE
1| C5| 1 uF| Digikey| 587−3247−1−ND| Taiyo Yuden| UMK107AB7105KA−T
1| D1| FSV330AF| ON

Semiconductor

TEST PROCEDURE

Equipment Needed
DC Source − 12 V ± 5% @ 1 A
2 − DC Voltmeter − 300 V dc minimum 0.1% accuracy or better
2 − DC Ammeter − 1 A dc minimum 0.1% accuracy or better
LED Load − 2.5 V − 5.0 V @ 1.0 A

The Connections

Connect the LED load board to the LED driver using the FPC cable provided in the kit.
Connect red (+) and black (−) leads through the ammeter to the LED load.
Connect a 12 V dc source to the input power connector.

NOTE: Unless otherwise specified, all voltage measurements are taken at the terminals of the UUT.
Functional Test Procedure

Set the LED Load for 3.5 V output.
Set the input voltage to 12 V.
Measure input voltage and current.
Measure output voltage and current.

Regulation
See Table 3.
Table 3. REGULATION

DAC Data| Iout Target| Output Current| Output Voltage| Input Voltage| Input Current
---|---|---|---|---|---
00 00| 0 A| | | |
0F F0| 1 A ± 5%| | | |
07 00| 0.5 A ± 5%| | | |

TEST DATA

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THERMAL IMAGE

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